Allergy skin testing uses tiny pricks in the skin to check for allergic reactions, typically to pollen, mold, pet dander, dust mites, and foods. Also called a skin prick, puncture, or scratch test, the procedure can test up to 40 different substances at one time. In adults, the test is usually done on the forearm; in children it is typically done on the back. The severity of the allergy is determined by the size of the raised, red, itchy bump (wheal) around the prick site. Skin testing is not painful, as the prick is extremely tiny, but it can be very itchy if your skin responds to the allergen. After the test, a nurse wipes the area with alcohol, which eases itching.